Hod Rod Deluxe Problems - Please Help

[Road King]

Totally new here and needing some help. My son has a US made HRD that has been acting up and is getting worse. We first noticed a drop in volume. Then the drive channel just stopped working all together. Now the volume is fluctuating dramatically. He noticed a few minutes ago that the second position power tube is glowing blue.
Any ideas?
Any and all help is greatly appreciated.

[CharlieP]

New power tubes may help.

[Mark Black]

The "Hot Rod" & "Blues" DeVille & Deluxe amps are noted for a few common problems:

Cracked solder joints especially at the PC-mounted tube sockets, jacks, controls, switches, & LED's. There may also be cracking at the solder joints of any large and/or heat-producing PC-mounted component, which brings us to another common problem -

There are two large "cement" (or "sandblock" if you prefer) resistors which run quite hot and are very prone to overheating/cooking-off the solder at their joints. The amps with the 470 ohm resistors have the most problems - a later redesign used 330 ohm with a different power transformer which lowered the applied voltage and dissipation in that part of the circuit.

For some reason, even though they are 1/2W rated, the plate resistors for the phase inverter tube are known to fail open or go very high in value (usually with little or no visible sign of defect).

Aside from these model-specific issues there can be simply dirty normalling switch contacts in the "Power Amp In" jack (check by using a cord from "Preamp Out" to "Power Amp In" to bypass the contacts). And yes - tubes could be at fault, but losing only one channel makes me think not - try swapping preamp tubes around to see if the problem is altered. The blue glow may or may not indicate a problem - some tubes glow more than others.

Try some searches on the forum for, variously "Blues Deville" (or Deluxe) and various permutations of HRD, "Hot Rod" and so forth. There have been a lot of posts regarding these amps.

This is also a good resource (very nicely done and with pictures):
The Unofficial Fender Hot Rod Deluxe Owner's Guide!

Look under "Repair Help"

Best of luck!

[stosostu]

Just a comment on the failure of the plate resistors in the HRD and similar amps. Even though these resistors are rated for 1/2 watt, which should be plenty, they are only rated for 250 V DC, and they have far more than that applied. I usually replace all of them with 1 watt, 500 V DC resistors on every HRD or similar that hits my bench, for the sake of less than a dollars worth of parts, it is a good investment.